Morbidly obese individuals with impaired fasting glucose have a specific pattern of insulin secretion and sensitivity: effect of weight loss after bariatric surgery

A pilot study of the effects of supervised exercise training on body composition, cardiometabolic risk factors, muscle strength and functional capacity in individuals with bariatric surgery

The main objective of this pilot study was to evaluate the effects of functional exercise training (FET) and home exercise training (HET) on body composition, cardiometabolic risk factors, muscle strength, and functional capacity in individuals with bariatric surgery. The sample of the study included 30 individuals who underwent bariatric surgery. The FET group had functional exercise training consisting of stretching, aerobic, strengthening, and balance exercises assigned by a physiotherapist (n = 15), and the HET group had the same exercises under supervision (n = 15). The training sessions were planned as × 3 per week for a period of 8 weeks. Body composition, cardiometabolic risk factors, cardiometabolic risk status, muscle strength, and functional capacity of all individuals were evaluated before and after training. According to the measurements, body weight (BW), body mass index (BMI), body fat mass (BFM), C-reactive protein, glycated hemoglobin, insulin resistance, cardiovascular risk total score, and ten-year cardiovascular percentage risk decreased significantly (p < 0.05), while HDL-C, leg, back, and hand grip strength (right-left), and walking distance increased significantly (p < 0.05) in the FET group. In the HET group, there were significant increases in body fat percentage (BFM %), BFM, and body muscle mass percentage (BMM %) (p < 0.05), while body muscle mass (BMM), right hand grip strength, leg and back muscle strength, and walking distance scores significantly decreased (p < 0.05). It was concluded that personalized and supervised FET has a positive effect on body composition, cardiometabolic risk factors, muscle strength, and functional capacity, and it can be recommended as a safe exercise model for bariatric surgery patients.

Improved Insulin Secretion Response and Beta-cell Function Correlated with Increased Prolactin Levels After Laparoscopic Sleeve Gastrectomy in Morbidly Obese Patients with Acanthosis Nigricans

OBJECTIVE

To explore insulin secretion patterns, β-cell function, and serum prolactin (PRL) concentrations in Chinese morbidly obese patients with Acanthosis nigricans (AN) and their alterations after laparoscopic sleeve gastrectomy (LSG).

METHODS

A total of 138 morbidly obese subjects undergoing LSG were categorized as simple obesity without AN (OB group, n = 55) and obesity with AN (AN group, n = 83). Oral glucose tolerance test (OGTT), PRL, and related metabolic indices were performed pre- and 12 months post-LSG. Insulin secretion patterns were derived from insulin secretion peak time during OGTT: type I (peak at 30 or 60 min) and type II (peak at 120 or 180 min).

RESULTS

Preoperatively, AN group showed significantly higher proportions of type II insulin secretion pattern, fasting insulin (FINS), and homeostatic model assessment of insulin resistance (HOMA-IR) whereas lower oral glucose insulin sensitivity (OGIS), insulinogenic index (IGI), and disposition index (DI) than OB group, which were improved significantly at 12 months postoperatively in both groups, more pronounced in AN group. Intriguingly, serum PRL declined substantially in AN group than OB group at baseline whereas elevated only in the AN group post-LSG. After adjusting for confounding factors, elevated PRL correlated significantly with increased IGI and DI, and decreased HOMA-IR in both genders, as well as increased OGIS in females, which was detected only in the AN group CONCLUSION: Morbidly obese patients with AN presented delayed insulin secretion response, impaired insulin secretion, and β-cell dysfunction, which were significantly improved by LSG and might benefit from elevated PRL.

Morbid Obesity in Women Is Associated with an Altered Intestinal Expression of Genes Related to Cancer Risk and Immune, Defensive, and Antimicrobial Response

Background: Little is known about the relation between morbid obesity and duodenal transcriptomic changes. We aimed to identify intestinal genes that may be associated with the development of obesity regardless of the degree of insulin resistance (IR) of patients. Material and Methods: Duodenal samples were assessed by microarray in three groups of women: non-obese women and women with morbid obesity with low and high IR. Results: We identified differentially expressed genes (DEGs) associated with morbid obesity, regardless of IR degree, related to digestion and lipid metabolism, defense response and inflammatory processes, maintenance of the gastrointestinal epithelium, wound healing and homeostasis, and the development of gastrointestinal cancer. However, other DEGs depended on the IR degree. We mainly found an upregulation of genes involved in the response to external organisms, hypoxia, and wound healing functions in women with morbid obesity and low IR. Conclusions: Regardless of the degree of IR, morbid obesity is associated with an altered expression of genes related to intestinal defenses, antimicrobial and immune responses, and gastrointestinal cancer. Our data also suggest a deficient duodenal immune and antimicrobial response in women with high IR.

Jejunal Insulin Signalling Is Increased in Morbidly Obese Subjects with High Insulin Resistance and Is Regulated by Insulin and Leptin

Little is known about the jejunal insulin signalling pathways in insulin resistance/diabetes states and their possible regulation by insulin/leptin. We study in jejunum the relation between insulin signalling and insulin resistance in morbidly obese subjects with low (MO-low-IR) or with high insulin resistance (MO-high-IR), and with type 2 diabetes treated with metformin (MO-metf-T2DM)), and the effect of insulin/leptin on intestinal epithelial cells (IEC). Insulin receptor substrate-1 (IRS1) and the catalytic p110β subunit (p110β) of phosphatidylinositol 3-kinase (PI3K) were higher in MO-high-IR than in MO-low-IR. The regulatory p85α subunit of PI3K (p85α)/p110β ratio was lower in MO-high-IR and MO-metf-T2DM than in MO-low-IR. Akt-phosphorylation in Ser473 was reduced in MO-high-IR compared with MO-low-IR. IRS1 and p110-β were associated with insulin and leptin levels. The improvement of body mass index (BMI) and HOMA-IR (homeostasis model assessment of insulin resistance index) after bariatric surgery was associated with a higher IRS1 and a lower p85α/p110β ratio. IEC (intestinal epithelial cells) incubation with a high glucose + insulin dose produced an increase of p85α and p110β. High dose of leptin produced an increase of IRS1, p85α and p110β. In conclusion, despite the existence of insulin resistance, the jejunal expression of genes involved in insulin signalling was increased in MO-high-IR. Their expressions were regulated mainly by leptin. IRS1 and p85α/p110β ratio was associated with the evolution of insulin resistance after bariatric surgery.

Delayed insulin secretion response during an OGTT is associated with an increased risk for incidence of diabetes in NGT subjects

AIMS

This study aimed to assess whether insulin secretion patterns during oral glucose tolerance tests (OGTTs) could predict future type 2 diabetes (T2D) in Chinese normal glucose tolerance (NGT) subjects.

METHODS

A total of 558 NGT, 419 newly diagnosed impaired glucose tolerance, and 694 newly diagnosed T2D patients were assessed. NGT subjects were grouped based on the time of peak insulin secretion during a 3h- OGTT; at 30min (InsP30), 60min (InsP60), 120min (InsP120), or 180min (InsP180), respectively. NGT subjects were followed up for an average duration of 5.58±1.08years. Beta-cell function was estimated by Stumvoll insulin secretion.

RESULTS

The InsP120 and InsP180 groups had lower Stumvoll first-phase insulin secretion levels compared with InsP30. At 5.58±1.08years, 25 (5.39%) NGT subjects had developed T2D. The cumulative incidence rate of diabetes was higher in the InsP120 and InsP180 groups (8.94%), compared with InsP30 (1.48%) (P<0.05). The adjusted relative risk for incident diabetes was 7.30 (95% CI: 1.53-34.72) times higher in the InsP120 and InsP180 groups.

CONCLUSIONS

NGT subjects with late insulin responses had defective early insulin secretion and were at higher risk of developing diabetes. Insulin secretion patterns could be a useful T2D predictor in the Chinese population.

Effects of sleeve gastrectomy on insulin resistance

BACKGROUND AND AIM

Obesity is a major risk factor for the onset of insulin resistance (IR), hyperinsulinemia and type 2 diabetes mellitus (T2DM) Evidence data has proven that beyond important weight loss bariatric surgery especially Roux-en-Y gastric bypass (RYGB) and bilio-pancreatic diversion (BPD) leads to significant early reduction of insulinemia and of IR calculated through the homeostatic model assessment (HOMA-IR), independently of fat mass decrease. Sleeve gastrectomy (SG) is now used as a sole weight loss operation with good results. Therefore, the aim of the present study was to investigate the early changes of fasting blood glucose, insulin and HOMA-IR in a group of morbidly obese (MO) patients i.e. at 7, 30 and 90 days after SG.

METHODS

The study included 20 MO patients (7 male and 13 female) submitted to SG. Anthropometrical (weight, body mass index -BMI, percent excess BMI loss -%EBMIL) and biochemical (plasma glucose, insulin and calculated HOMA-IR ) evaluation were performed before and at 7, 30 and 90 days after SG. In addition, a second group of 10 normal weight healthy subjects with a BMI ranging form 19 kg/m(2) to 23.14 kg/m(2), matched for age and gender was investigated.

RESULTS

Plasma glucose (p=0.018), insulin (p=0.004) and HOMA-IR (p=0.006) values were statistically different between the studied groups. After surgery, at every follow-up point, there were statistically different weight and BMI mean values relative to the operation day (p<0.003). BMI, decreased at 7 days (estimated reduction=2.79; 95% CI:[2.12;3.45]), at 30 days (estimated reduction=5.65; 95% CI:[3.57;7.73]) and at 90 days (estimated reduction=10.88; 95% CI:[7.35;14.41]) respectively after SG. We noted a tendency toward statistical significant change of mean insulin values at 7 days after surgery (corrected p=0.075), no statistical change at 30 days (corrected p=0.327) and a significant change at 90 days (corrected p=0.027) after SG as compared to baseline. There was a significant change in mean values of HOMA-IR at 30 days (corrected p=0.009) and at 90 days (corrected p=0.021) after the operation day.

CONCLUSIONS

The present study showed important early changes consisting in reductions of mean values of plasma insulin and HOMA-IR after SG.

A role for exercise after bariatric surgery?

Obesity predisposes an individual to develop numerous comorbidities, including type 2 diabetes, and represents a major healthcare issue in many countries worldwide. Bariatric surgery can be an effective treatment option, resulting in profound weight loss and improvements in metabolic health; however, not all patients achieve similar weight loss or metabolic improvements. Exercise is an excellent way to improve health, with well-characterized physiological and psychological benefits. In the present paper we review the evidence to determine whether there may be a role for exercise as a complementary adjunct therapy to bariatric surgery. Objectively measured physical activity data indicate that most patients who undergo bariatric surgery do not exercise enough to reap the health benefits of exercise. While there is a dearth of data on the effects of exercise on weight loss and weight loss maintenance after surgery, evidence from studies of caloric restriction and exercise suggest that similar adjunctive benefits may be extended to patients who perform exercise after bariatric surgery. Recent evidence from exercise interventions after bariatric surgery suggests that exercise may provide further improvements in metabolic health compared with surgery-induced weight loss alone. Additional randomized controlled exercise trials are now needed as the next step to more clearly define the potential for exercise to provide additional health benefits after bariatric surgery. This valuable evidence will inform clinical practice regarding much-needed guidelines for exercise after bariatric surgery.

Insulin Sensitivity and β-Cell Function Improve after Gastric Bypass in Severely Obese Adolescents

OBJECTIVE

To test the hypothesis that insulin secretion and insulin sensitivity would be improved in adolescents after Roux-en-Y gastric bypass (RYGB).

STUDY DESIGN

A longitudinal study of 22 adolescents and young adults without diabetes undergoing laparoscopic RYGB (mean age 17.1 ± 1.42 years; range 14.5-20.1; male/female 8/14; Non-Hispanic White/African American 17/5) was conducted. Intravenous glucose tolerance tests were done to obtain insulin sensitivity (insulin sensitivity index), insulin secretion (acute insulin response to glucose ), and the disposition index as primary outcome variables. These variables were compared over the 1 year of observation using linear mixed modeling.

RESULTS

In the 1-year following surgery, body mass index fell by 38% from a mean of 61 ± 12.3 to 39 ± 8.0 kg/m(2) (P < .01). Over the year following surgery, fasting glucose and insulin values declined by 54% and 63%, respectively. Insulin sensitivity index increased 300% (P < .01), acute insulin response to glucose decreased 56% (P < .01), leading to a nearly 2-fold increase in the disposition index (P < .01). Consistent with improved β-cell function, the proinsulin to C-peptide ratio decreased by 21% (P < .01).

CONCLUSIONS

RYGB reduced body mass index and improved both insulin sensitivity and β-cell function in severely obese teens and young adults. These findings demonstrate that RYGB is associated with marked metabolic improvements in obese young people even as significant obesity persists.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00360373.

C-peptide modifies leptin and visfatin secretion in human adipose tissue

OBJECTIVE

The effects of C-peptide on adipose tissue, an organ involved in the development of obesity and insulin resistance, are not yet well known. The aim of this study was to determine whether C-peptide could be involved in the regulation of the adipocytokine synthesis in human visceral adipose tissue.

METHODS

The association between C-peptide and different serum adipocytokines, with an intravenous glucose tolerance test (IVGTT), and in an in vitro study in subjects without obesity and in subjects with morbid obesity were analyzed.

RESULTS

In different multiple regression analysis models, C-peptide and C-peptide increase above basal levels during total IVGTT and between 0 and 10 min were associated positively with leptin and negatively with visfatin. Rhodamine-labeled C-peptide binds to human adipocytes, and this binding was blocked with excess of unlabeled C-peptide. Exposure of human visceral explants and adipocytes from subjects with morbid obesity to C-peptide at 1 and 10 nM induced a significant increase in leptin and a decrease in visfatin secretion. In subjects without obesity, these C-peptide effects were found mainly at 10 nM. These effects can be inhibited by phosphatidylinositol 3-kinase (PI3K) or protein kinase B (PKB) inhibitors.

CONCLUSIONS

C-peptide may be involved in the regulation of leptin and visfatin secretion, molecules intimately involved in energy homeostasis processes, through PI3K or PKB pathways.

Effects of gastric bypass on type 2 diabetes in patients with BMI 30 to 35

BACKGROUND

This study aims to investigate if the benefits on glycemic control following Roux-en-Y gastric bypass (RYGB) in morbidly obese type 2 diabetes (T2DM) patients are maintained in the 30-35 kg/m(2) BMI (body mass index) range, comparing results with those in literature.

METHODS

The study participants were twenty T2DM patients aging 35-70 years, BMI 30.0-34.9 kg/m(2), minimum diabetes duration 3 years, glycosylated haemoglobin (HbA1c) ≥7.5% despite good clinical practice medical therapy, submitted to laparoscopic RYGB, and monitored during 36 months. Twenty-seven matched diabetic patients as controls.

RESULTS

Five females, mean age 57 (42-69) years, weight 96.0 (70-111) kg, BMI 32.9 (30.3-34.9) kg/m(2), waist circumference 112 (100-128) cm, diabetes duration 14 (3-28) years, HbA1c 9.5 (7.5-14.2) %, and C-peptide 3.2 (1,6-9.1) mcg/l. Ten patients were on insulin. There was no mortality, and there were two major late complications. BMI and waist decreased stabilizing around 25 kg/m(2) and 92 cm. Fasting serum glucose and HbA1c reached values around 150 mg/dl and 7%, which subsequently maintained. There was remission in 25% of cases, control 45%, and all the others improved. HOMA-IR and insulin sensitivity index normalized at 1 month, then maintained. AIR and insulinogenic index showed no postoperative changes. Diabetes remission correlated negatively with duration (p < 0.05; r (2) = 0.61), while control positively with C-peptide (p < 0.05; r (2) = 0.19). In the control group, FSG, HbA1c, serum triglyceride, and cholesterol significantly decreased with considerable progressive increase of antidiabetic/antihyperlipemic therapy. All patients had HbA1c >7% at 2-3 years.

CONCLUSIONS

Glycemic control obtained by RYGB in this study was less good than that reported by others, apparently due to different patient selection criteria. Our results do not support RYGB weight loss-independent effect on beta-cell function in the T2DM patients with BMI 30-35 kg/m(2).

Immediate enhancement of first-phase insulin secretion and unchanged glucose effectiveness in patients with type 2 diabetes after Roux-en-Y gastric bypass

Roux-en-Y gastric bypass surgery (RYGB) in patients with type 2 diabetes often leads to early disease remission, and it is unknown to what extent this involves improved pancreatic β-cell function per se and/or enhanced insulin- and non-insulin-mediated glucose disposal (glucose effectiveness). We studied 30 obese patients, including 10 with type 2 diabetes, 8 with impaired glucose tolerance, and 12 with normal glucose tolerance before, 1 wk, and 3 mo after RYGB, using an intravenous glucose tolerance test (IVGTT) to estimate first-phase insulin response, insulin sensitivity (Si), and glucose effectiveness with Bergman's minimal model. In the fasting state, insulin sensitivity was estimated by HOMA-S and β-cell function by HOMA-β. Moreover, mixed-meal tests and oral GTTs were performed. In patients with type 2 diabetes, glucose levels normalized after RYGB, first-phase insulin secretion in response to iv glucose increased twofold, and HOMA-β already improved 1 wk postoperatively, with further enhancements at 3 mo. Insulin sensitivity increased in the liver (HOMA-S) at 1 wk and at 3 mo in peripheral tissues (Si), whereas glucose effectiveness did not improve significantly. During oral testing, GLP-1 responses and insulin secretion increased regardless of glucose tolerance. Therefore, in addition to increased insulin sensitivity and exaggerated postprandial GLP-1 levels, diabetes remission after RYGB involves early improvement of pancreatic β-cell function per se, reflected in enhanced first-phase insulin secretion to iv glucose and increased HOMA-β. A major role for improved glucose effectiveness after RYGB was not supported by this study.

Sagittal abdominal diameter and visceral adiposity: correlates of beta-cell function and dysglycemia in severely obese women

BACKGROUND

In the context of increasing obesity prevalence, the relationship between large visceral adipose tissue (VAT) volumes and type 2 diabetes mellitus (T2DM) is unclear. In a clinical sample of severely obese women (mean body mass index [BMI], 46 kg/m(2)) with fasting normoglycemia (n = 40) or dysglycemia (impaired fasting glucose + diabetes; n = 20), we sought to determine the usefulness of anthropometric correlates of VAT and associations with dysglycemia.

METHODS

VAT volume was estimated using multi-slice computer tomography; anthropometric surrogates included sagittal abdominal diameter (SAD), waist circumference (WC) and BMI. Insulin sensitivity (Si), and beta-cell dysfunction, measured by insulin secretion (AIRg) and the disposition index (DI), were determined by frequently sampled intravenous glucose tolerance test.

RESULTS

Compared to fasting normoglycemic women, individuals with dysglycemia had greater VAT (P < 0.001) and SAD (P = 0.04), but BMI, total adiposity and Si were similar. VAT was inversely associated with AIRg and DI after controlling for ancestry, Si, and total adiposity (standardized beta, -0.32 and -0.34, both P < 0.05). In addition, SAD (beta = 0.41, P = 0.02) was found to be a better estimate of VAT volume than WC (beta = 0.32, P = 0.08) after controlling for covariates. Receiver operating characteristic analysis showed that VAT volume, followed by SAD, outperformed WC and BMI in identifying dysglycemic participants.

CONCLUSIONS

Increasing VAT is associated with beta-cell dysfunction and dysglycemia in very obese women. In the presence of severe obesity, SAD is a simple surrogate of VAT, and an indicator of glucose dysregulation.

Metabolic surgery: shifting the focus from glycaemia and weight to end-organ health

Bariatric surgery is the most effective treatment for weight loss and glycaemic control. The focus of clinical studies and clinical experience has predominantly been on the numerical reductions of bodyweight and glucose after surgery. In this Series paper, we examine evidence on the efficacy of bariatric surgery for pancreatic, renal, retinal, peripheral nervous, cardiovascular, hepatic, and reproductive end-organ damage or disease. The overall conclusions are that, in most cases, patients' end-organ damage is expected to either stabilise or improve postoperatively. However, some of these clinical outcomes have not been assessed with robust methods and, in many cases, do not have support from randomised controlled clinical trials comparing bariatric surgery with non-surgical interventions. Such trials are urgently needed to inform patients and clinicians on whether the risks of surgery outweigh the significant benefits for end-organ health.

Exaggerated release and preserved insulinotropic action of glucagon-like peptide-1 underlie insulin hypersecretion in glucose-tolerant individuals after Roux-en-Y gastric bypass

AIMS/HYPOTHESIS

Roux-en-Y gastric bypass (RYGB) improves glycaemic control in part by increasing postprandial insulin secretion through exaggerated glucagon-like peptide (GLP)-1 release. However, it is unknown whether islet cell responsiveness to i.v. glucose, non-glucose (arginine) and incretin hormones, including GLP-1, is altered.

METHODS

Eleven severely obese glucose-tolerant individuals underwent three hyperglycaemic clamps with arginine bolus and co-infusion of either GLP-1, glucose-dependent insulinotropic polypeptide (GIP) or saline before, and at 1 week and 3 months after RYGB. In addition, an OGTT was performed before and 3 months after surgery.

RESULTS

After RYGB, insulin sensitivity improved at 1 week and 3 months, while insulin stimulation and glucagon suppression in response to the clamp with saline co-infusion were largely unaltered. The influence of i.v. GLP-1 and GIP on insulin and glucagon secretion was also unchanged postoperatively. In response to the postoperative OGTT at 3 months, insulin and GLP-1, but not GIP, secretion increased. Furthermore, the glucose profile during the OGTT was altered, with a substantial reduction in 2 h plasma glucose and a paradoxical hypersecretion of glucagon.

CONCLUSIONS/INTERPRETATION

After RYGB, insulin hypersecretion is linked to the oral, but not the i.v., route of administration and is associated with exaggerated release and preserved insulinotropic action of GLP-1, while both the secretion and action of GIP are unchanged. The results highlight the importance of increased GLP-1 secretion for improving postoperative glucose metabolism.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01559779.

Effects of bariatric surgery on glucose homeostasis and type 2 diabetes

Obesity is an important risk factor for type 2 diabetes mellitus (T2DM). Weight loss improves the major factors involved in the pathogenesis of T2DM, namely insulin action and beta cell function, and is considered a primary therapy for obese patients who have T2DM. Unfortunately, most patients with T2DM fail to achieve successful weight loss and adequate glycemic control from medical therapy. In contrast, bariatric surgery causes marked weight loss and complete remission of T2DM in most patients. Moreover, bariatric surgical procedures that divert nutrients away from the upper gastrointestinal tract are more successful in producing weight loss and remission of T2DM than those that simply restrict stomach capacity. Although upper gastrointestinal tract bypass procedures alter the metabolic response to meal ingestion, by increasing early postprandial plasma concentrations of glucagon-like peptide 1 and insulin, it is not clear whether these effects make an important contribution to long-term control of glycemia and T2DM once substantial surgery-induced weight loss has occurred. Nonetheless, the effects of surgery on body weight and metabolic function indicate that bariatric surgery should be part of the standard therapy for T2DM. More research is needed to advance our understanding of the physiological effects of different bariatric surgical procedures and possible weight loss-independent factors that improve metabolic function and contribute to the resolution of T2DM.

Acute and long-term effects of Roux-en-Y gastric bypass on glucose metabolism in subjects with Type 2 diabetes and normal glucose tolerance

Our aim was to study the potential mechanisms responsible for the improvement in glucose control in Type 2 diabetes (T2D) within days after Roux-en-Y gastric bypass (RYGB). Thirteen obese subjects with T2D and twelve matched subjects with normal glucose tolerance (NGT) were examined during a liquid meal before (Pre), 1 wk, 3 mo, and 1 yr after RYGB. Glucose, insulin, C-peptide, glucagon-like peptide-1 (GLP-1), glucose-dependent-insulinotropic polypeptide (GIP), and glucagon concentrations were measured. Insulin resistance (HOMA-IR), β-cell glucose sensitivity (β-GS), and disposition index (D(β-GS): β-GS × 1/HOMA-IR) were calculated. Within the first week after RYGB, fasting glucose [T2D Pre: 8.8 ± 2.3, 1 wk: 7.0 ± 1.2 (P < 0.001)], and insulin concentrations decreased significantly in both groups. At 129 min, glucose concentrations decreased in T2D [Pre: 11.4 ± 3, 1 wk: 8.2 ± 2 (P = 0.003)] but not in NGT. HOMA-IR decreased by 50% in both groups. β-GS increased in T2D [Pre: 1.03 ± 0.49, 1 wk: 1.70 ± 1.2, (P = 0.012)] but did not change in NGT. The increase in DI(β-GS) was 3-fold in T2D and 1.5-fold in NGT. After RYGB, glucagon secretion was increased in response to the meal. GIP secretion was unchanged, while GLP-1 secretion increased more than 10-fold in both groups. The changes induced by RYGB were sustained or further enhanced 3 mo and 1 yr after surgery. Improvement in glycemic control in T2D after RYGB occurs within days after surgery and is associated with increased insulin sensitivity and improved β-cell function, the latter of which may be explained by dramatic increases in GLP-1 secretion.

Mechanisms of improved glycaemic control after Roux-en-Y gastric bypass

Roux-en-Y gastric bypass (RYGB) greatly improves glycaemic control in morbidly obese patients with type 2 diabetes, in many even before significant weight loss. Understanding the responsible mechanisms may contribute to our knowledge of the pathophysiology of type 2 diabetes and help identify new drug targets or improve surgical techniques. This review summarises the present knowledge based on pathophysiological studies published during the last decade. Taken together, two main mechanisms seem to be responsible for the early improvement in glycaemic control after RYGB: (1) an increase in hepatic insulin sensitivity induced, at least in part, by energy restriction and (2) improved beta cell function associated with an exaggerated postprandial glucagon-like peptide 1 secretion owing to the altered transit of nutrients. Later a weight loss induced improvement in peripheral insulin sensitivity follows.

Relationship between the preoperative body mass index and the resolution of metabolic syndrome following Roux-en-Y gastric bypass

BACKGROUND

The increased prevalence of overweight and obesity has reached alarming proportions worldwide and has serious health implications, including an association with an increase in metabolic syndrome. Among the methods to control metabolic syndrome, bariatric surgery plays an important role and can provide a significant improvement in the components of metabolic syndrome.

OBJECTIVE

The aim of this study was to determine the relationship between the preoperative body mass index (BMI) and the postoperative resolution of metabolic syndrome [using the National Cholesterol Education Program (NCEP ATP III criteria)] in patients undergoing Roux-en-Y gastric bypass (RYGB).

METHODS

Retrospective analysis of a consecutive series of cases, stratified by BMI into three groups (group 1, BMI <40 kg/m(2), group 2, BMI 40-49.9 kg/m(2), and group 3, BMI 50 ≥ kg/m(2)) consisting of both sexes between 20 and 60 years of age. The cohort consisted of 149 patients undergoing RYGB. Anthropometric, biochemical, and clinical evaluations were performed preoperatively and then at 30 and 180 days postoperatively.

RESULTS

The average age was 40 years, and the patients were predominately female (72%). At the end of the study period, all groups showed a significant reduction in metabolic syndrome compared with preoperative levels. Logistic regression showed a higher percentage of metabolic syndrome in patients in group 3 after 180 days.

CONCLUSION

There was significant resolution of metabolic syndrome in all groups, independently of the preoperative BMI. However, in group 3 (BMI ≥ 50 kg/m(2)), 22% of individuals still presented with metabolic syndrome at 180 days postoperatively (P=0.03).

Insulin resistance and bariatric surgery

The objective of this article is to systematically review the changes in insulin resistance after various types of bariatric surgical procedures. A Pubmed and EMBASE search for studies measuring insulin resistance before and after bariatric surgery was done and all original research articles from 1980 to present (2011) were included. Only the currently widely performed bariatric procedures were included. A meta-analysis of change in HOMA-IR was conducted, grouping studies with similar duration of follow-up. The percentage decrease in HOMA-IR at <=2 weeks, 1 month, 3 months, 6 months, 12 months and >16-18 months was found to be (mean ± standard error) -33.48 ± 5.78, -46.43 ± 6.99, -38.79 ± 9.64, -58.62 ± 7.38, -44.91 ± 7.98 and -67.04 ± 10.78%, respectively. RYGB (gastric bypass) and BPD (biliopancreatic diversion) produced a significant decrease in insulin resistance at 2 weeks after surgery, while LSG (sleeve gastrectomy) was strongly trending. LSG produced an earlier decrease in insulin resistance when compared to LAGB (gastric banding). RYGB, BPD and LSG produce an early decrease in insulin resistance through yet unknown mechanisms.

De novo lipogenesis in adipose tissue is associated with course of morbid obesity after bariatric surgery

Objective

De novo lipogenesis is involved in fatty acid biosynthesis and could be involved in the regulation of the triglyceride storage capacity of adipose tissue. However, the association between lipogenic and lipolytic genes and the evolution of morbidly obese subjects after bariatric surgery remains unknown. In this prospective study we analyze the association between the improvement in the morbidly obese patients as a result of bariatric surgery and the basal expression of lipogenic and lipolytic genes.

Methods

We study 23 non diabetic morbidly obese patients who were studied before and 7 months after bariatric surgery. Also, we analyze the relative basal mRNA expression levels of lipogenic and lipolytic genes in epiploic visceral adipose tissue (VAT) and abdominal subcutaneous adipose tissue (SAT).

Results

When the basal acetyl-CoA carboxylase 1 (ACC1), acetyl-CoA synthetase 2 (ACSS2) and ATP citrate lyase (ACL) expression in SAT was below percentile-50, there was a greater decrease in weight (P = 0.006, P = 0.034, P = 0.026), body mass index (P = 0.008, P = 0.033, P = 0.034) and hip circumference (P = 0.033, P = 0.021, P = 0.083) after bariatric surgery. In VAT, when the basal ACSS2 expression was below percentile-50, there was a greater decrease in hip circumference (P = 0.006). After adjusting for confounding variables in logistic regression models, only the morbidly obese patients with SAT or VAT ACSS2 expression≥P50 before bariatric surgery had a lower percentage hip circumference loss (<P50) after bariatric surgery (SAT: P = 0.039; VAT: P = 0.033).

Conclusions

A lower basal ACSS2, ACC1 and ACL expression, genes involved in de novo lipogenesis, is associated with a better evolution of anthropometric variables after bariatric surgery. Thus, the previous state of the pathways involved in fatty acid metabolism may have repercussions on the improvement of these patients.

Bypass of the duodenum improves insulin resistance much more rapidly than sleeve gastrectomy

BACKGROUND

Obesity is very often accompanied by other diseases, with the most common type 2 diabetes mellitus and cardiovascular complications. Bariatric surgery is the most effective strategy for treating morbidly obese patients. We evaluated the metabolic changes that occur in the early stage after 2 types of bariatric surgery, biliopancreatic diversion of Scopinaro (BPD) and sleeve gastrectomy (SG), in morbidly obese patients.

METHODS

The study was undertaken in 31 nondiabetic morbidly obese patients (7 men and 24 women). Of the 31 patients, 18 underwent BPD and 13 underwent SG. All patients were examined before bariatric surgery (baseline) and at 15, 30, 45, and 90 days postoperatively.

RESULTS

Significant improvement occurred in the anthropometric variables after the 2 types of bariatric surgery, without significant differences between the 2 types of interventions. In patients undergoing BPD, the serum glucose, cholesterol, triglycerides, high-density lipoprotein cholesterol, and free fatty acids were significantly reduced. The changes that occurred in these biochemical variables after SG were not significant. Insulin resistance decreased significantly during the 90 days after surgery, with the greatest decrease at 15 days. However, in the patients who underwent SG, insulin resistance worsened at 15 days and later diminished.

CONCLUSION

The results of the present study have shown that the surgical technique that excludes the duodenum (i.e., BPD) has immediate postoperative changes in the degree of insulin resistance in morbidly obese patients compared to those techniques that do not exclude the duodenum (i.e., SG).

Stearoyl-CoA desaturase-1 is associated with insulin resistance in morbidly obese subjects

Animal studies have revealed the association between stearoyl-CoA desaturase 1 (SCD1) and obesity and insulin resistance. However, only a few studies have been undertaken in humans. We studied SCD1 in visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) from morbidly obese patients and their association with insulin resistance, sterol regulatory element binding protein-1 (SREBP-1) and ATPase p97, proteins involved in SCD1 synthesis and degradation. The insulin resistance was calculated in 40 morbidly obese patients and 11 overweight controls. Measurements were made of VAT and SAT SCD1, SREBP-1 and ATPase p97 mRNA expression and protein levels. VAT and SAT SCD1 mRNA expression levels in the morbidly obese patients were significantly lower than in the controls (P = 0.006), whereas SCD1 protein levels were significantly higher (P < 0.001). In the morbidly obese patients, the VAT SCD1 protein levels were decreased in patients with higher insulin resistance (P = 0.007). However, SAT SCD1 protein levels were increased in morbidly obese patients with higher insulin resistance (P < 0.05). Multiple linear regressions in the morbidly obese patients showed that the variable associated with the SCD1 protein levels in VAT was insulin resistance, and the variables associated with SCD1 protein levels in SAT were body mass index (BMI) and ATPase p97. In conclusion, these data suggest that the regulation of SCD1 is altered in individuals with morbid obesity and that the SCD1 protein has a different regulation in the two adipose tissues, as well as being closely linked to the degree of insulin resistance.

Obesity and insulin resistance-related changes in the expression of lipogenic and lipolytic genes in morbidly obese subjects

BACKGROUND

The storage capacity of adipose tissue may be an important factor linking obesity, insulin resistance (IR), and associated morbidities. The aim of this study was to analyze the expression of lipogenic and lipolytic genes in adipose tissue and the influence of IR.

METHODS

We studied the mRNA expression of peroxisome proliferator-activated receptor-γ (PPARγ) and lipogenic and lipolytic enzymes in the visceral (VAT) and subcutaneous adipose tissue (SAT) from 23 morbidly obese patients (MO; 13 with low IR and ten with high IR) and from 15 healthy, lean controls.

RESULTS

In the VAT and SAT from the MO, we found an increased expression of PPARγ (p = 0.001 and p = 0.022, respectively), acyl-coenzyme A (CoA)/cholesterol acyltransferase (p < 0.001 and p < 0.001), aquaporin 7 (p < 0.001 and p = 0.003), and adipose triglyceride lipase (p < 0.001 and p < 0.001) and a reduced expression of acetyl-coenzyme A carboxylase (p = 0.004 and p < 0.001), independently of the state of IR. The expression of phosphoenolpyruvate carboxykinase and acyl-CoA synthetase, however, was significantly lower in the MO with high IR (p < 0.05). Glycerol kinase (p = 0.010), hormone-sensitive lipase (p < 0.001), and perilipin (p = 0.006) were only significantly increased in VAT. Acyl-CoA synthetase (p = 0.012) and fatty acid binding protein-4 (p = 0.003) were only significantly decreased in SAT. The expression of the genes studied was only greater in the SAT than the VAT in the controls.

CONCLUSION

Our results show an upregulation of genes facilitating triglyceride/fatty acid cycling and a reduction in the genes involved in de novo synthesis of fatty acids in morbid obesity. The expression of some of the genes studied seems to be related with the state of IR. VAT and SAT differ metabolically and also between controls and MO.

Improvement in ß-cell function in patients with normal and hyperglycemia following Roux-en-Y gastric bypass surgery

Glycemic disorders resolve following Roux-en-Y gastric bypass (RYGB) surgery, but early and longer-term mechanisms regarding effects on β-cell dysfunction as well as relationships with decreasing adiposity are not well understood. We evaluated longitudinal changes in peripheral insulin sensitivity (Si), the acute insulin response to glucose (AIRg), and the composite estimate of β-cell function, the disposition index (DI), over 24 mo via frequently sampled intravenous glucose tolerance testing in severely obese women who had fasting normoglycemia (n = 16) and hyperglycemia (n = 11) before RYGB surgery; homeostatic model assessment (HOMA-IR) estimated insulin resistance; air displacement plethysmography determined adipose tissue mass. At baseline, subjects with normoglycemia had adequate DI associated with elevated AIRg, but DI was markedly reduced in subjects with hyperglycemia. Within 1-6 mo post-RYGB, glycemic control was normalized in subjects with hyperglycemia related to reduced HOMA-IR (-54% at 1 mo, P < 0.005) and increased DI (23-fold at 6 mo vs. baseline, P < 0.05). Over 24 mo, DI improved in subjects with hyperglycemia (15-fold vs. baseline, P < 0.005) and also modestly in subjects with normoglycemia (58%, P < 0.05), due largely to increased Si. Decreasing adiposity correlated with longer-term HOMA-IR and Si values at 6 and 24 mo, respectively. In patients exhibiting fasting hyperglycemia before surgery, β-cell function improved early following RYGB, due largely to increases in insulin secretion. For both normoglycemic and hyperglycemic subjects, further improvement or stabilization of β-cell function over the 2 yr is due largely to improved Si associated with reduced adiposity.

Beta-cell function improvement after biliopancreatic diversion in subjects with type 2 diabetes and morbid obesity

In subjects with obesity and type 2 diabetes mellitus (T2DM), biliopancreatic diversion (BPD) improves glucose stimulated insulin secretion, whereas the effects on other secretion mechanisms are still unknown. Our objective was to evaluate the early effects of BPD on nonglucose-stimulated insulin secretion. In 16 morbid obese subjects (9 with T2DM and 7 with normal fasting glucose (NFG)), we measured insulin secretion after glucose-dependent arginine stimulation test and after intravenous glucose tolerance test (IVGTT) before and 1 month after BPD. After surgery the mean weight lost was 13% in both groups. The acute insulin response during IVGTT was improved in T2DM after BDP (from 55 +/- 10 to 277 +/- 91 pmol/l, P = 0.03). A reduction of insulin response to arginine was observed in NFG, whereas opposite was found in T2DM. In particular, acute insulin response to arginine at basal glucose concentrations (AIR(basal)) was reduced but insulin response at 14 mmol/l of plasma glucose (AIR(14)) was increased. Therefore, after BPD any statistical difference in AIR(14) between NFG and T2DM disappeared (1,032 +/- 123 for NFG and 665 +/- 236 pmol/l for T2DM, P = ns). The same was observed for Slope(AIR), a measure of glucose potentiation, reduced in T2DM before BPD but increased after surgery, when no statistically significant difference resulted compared with NFG (Slope(AIR) after BPD: 78 +/- 11 in NFG and 56 +/- 18 pmol/l in T2DM, P = ns). In conclusion, in obese T2DM subjects 1 month after BPD we observed a great improvement of both glucose- and nonglucose-stimulated insulin secretions. The mechanisms by which BDP improve insulin secretion are still unknown.

"Metabolic" surgery for treatment of type 2 diabetes mellitus

OBJECTIVE

To discuss the potential contribution of "metabolic" surgery in providing optimal management of patients with type 2 diabetes mellitus (T2DM).

METHODS

A literature search was performed with use of PubMed, and the clinical experience of the authors was also considered.

RESULTS

Bariatric-or, more appropriately, metabolic-surgical procedures have been shown to provide dramatic improvement in blood glucose levels, blood pressure, and lipid control in obese patients with T2DM. In these patients, metabolic surgery involves a low risk of short-term mortality and a significant long-term survival advantage, whereas the diagnosis of diabetes is associated with significant long-term mortality. Experimental studies in animals and clinical trials suggest that gastrointestinal bypass procedures can control diabetes and associated metabolic alterations by mechanisms independent of weight loss. As a result, the use of bariatric surgery and experimental gastrointestinal manipulations to treat T2DM is increasing, even among less obese patients. Although body mass index (BMI) currently is the most important factor for identifying candidates for bariatric surgery, evidence shows that a specific cutoff BMI value cannot accurately predict successful surgical outcomes. Furthermore, BMI appears limited in defining the risk profile for patients with T2DM.

CONCLUSION

Current BMI-based criteria for performance of bariatric surgery are not adequate for determining eligibility for operative treatment in patients with diabetes. Large clinical trials, comparing bariatric surgery versus optimal medical care of patients with T2DM, should be given priority in order to define the role of surgery in the management of diabetes. Recognizing the need to work as a multidisciplinary team that includes endocrinologists and surgeons is an initial step in addressing the issues and opportunities that surgery offers to diabetes care and research.

Apelin levels are increased in morbidly obese subjects with type 2 diabetes mellitus

BACKGROUND

The physiological role of apelin in obesity and diabetes remains unclear. Although apelin has been studied in persons with different conditions, no studies have yet examined the joint influence of obesity and diabetes on apelin levels. We measured the changes in apelin levels in morbidly obese subjects, with and without diabetes, and in the inverse situation of improvement in carbohydrate metabolism as a result of bariatric surgery.

METHODS

The study was undertaken in 54 morbidly obese persons, 16 of whom had type 2 diabetes mellitus, before and 7 months after undergoing bariatric surgery, and in 12 healthy, nonobese persons. Measurements were made of apelin levels and insulin sensitivity by an intravenous glucose tolerance test.

RESULTS

The apelin levels in the morbidly obese patients prior to surgery were significantly higher than those of the controls only when the morbidly obese subjects were diabetic (P < 0.005). Apelin levels correlated significantly in the morbidly obese patients with serum triglycerides (r = 0.292, P = 0.032) and glucose (r = 0.337, P = 0.039). Bariatric surgery resulted in a significant decrease in apelin levels only in the morbidly obese subjects with impaired fasting glucose or diabetes. The change in apelin levels correlated significantly in the morbidly obese patients with the changes in serum glucose (r = 0.338, P = 0.038) and insulin sensitivity (r = -0.417, P = 0.043).

CONCLUSIONS

This study demonstrates that obesity is not the main determinant of the rise in apelin levels. The association between apelin levels and glucose concentrations and insulin sensitivity provides evidence that apelin may play a role in the pathogenesis of diabetes.

Changes in the serum composition of free-fatty acids during an intravenous glucose tolerance test

Recent studies suggest that measuring the free-fatty acids (FFA) during an intravenous glucose tolerance test (IVGTT) may provide information about the metabolic associations between serum FFA and carbohydrate and insulin metabolism. We evaluated the FFA profile during an IVGTT and determined whether this test changes the composition and concentration of FFA. An IVGTT was given to 38 severely obese persons before and 7 months after undergoing bariatric surgery and also to 12 healthy, nonobese persons. The concentration and composition of the FFA were studied at different times during the test. The concentration of FFA fell significantly faster during the IVGTT in the controls and in the severely obese persons with normal-fasting glucose (NFG) than in the severely obese persons with impaired-fasting glucose (IFG) or type 2 diabetes mellitus (T2DM) (P < 0.05). Significant differences were found in the time to minimum serum concentrations of FFA (control = NFG < IFG < T2DM) (P < 0.001). These variables improved after bariatric surgery in the three groups. The percentage of monounsaturated and n-6 polyunsaturated FFA in the control subjects and in the obese persons, both before and after surgery, decreased significantly during the IVGTT. In conclusion, during an IVGTT, severely obese persons with IFG or T2DM experienced a lower fall in the FFA than the severely obese persons with NFG and the controls, becoming normal after bariatric surgery.

Improved carbohydrate metabolism after bariatric surgery raises antioxidized LDL antibody levels in morbidly obese patients

OBJECTIVE

Antioxidized LDL (anti-oxLDL) antibodies have recently been suggested to be protective against the development of diabetes. We measured the changes in anti-oxLDL antibody levels in the inverse situation of improvement in carbohydrate metabolism.

RESEARCH DESIGN AND METHODS

The study was undertaken in 73 morbidly obese individuals, 21 of whom had type 2 diabetes, before and 7 months after they underwent bariatric surgery and in 11 healthy, nonobese individuals. Measurements were made of the area under the curve of glucose (AUC(Glu)) by an intravenous glucose tolerance test and of oxidized LDL (oxLDL) and IgG and IgM anti-oxLDL antibodies.

RESULTS

The morbidly obese patients with diabetes had significantly higher levels of oxLDL compared with the morbidly obese patients with normal fasting glucose and the control subjects and significantly lower levels of IgM anti-oxLDL antibodies. An inverse correlation was found between the levels of oxLDL and IgM anti-oxLDL antibodies (r = -0.352, P = 0.012). Although the levels of IgG and IgM anti-oxLDL antibodies rose after surgery, this increase was only significant in the diabetic patients, who experienced an improvement in their metabolic profile. Different multiple linear regression models showed that the AUC(Glu) was the main factor explaining the behavior of the levels of oxLDL and anti-oxLDL antibodies.

CONCLUSIONS

We found a close association between carbohydrate metabolism and IgM anti-oxLDL antibodies, which were significantly reduced in the morbidly obese patients with diabetes. The improvement in carbohydrate metabolism after bariatric surgery led to a significant increase in the levels of IgG and IgM anti-oxLDL antibodies.

Restoration of acute insulin response in T2DM subjects 1 month after biliopancreatic diversion

OBJECTIVE

Biliopancreatic diversion (BPD) restores normal glucose tolerance in a few weeks in morbid obese subjects with type 2 diabetes, improving insulin sensitivity. However, there is less known about the effects of BPD on insulin secretion. We tested the early effects of BPD on insulin secretion in obese subjects with and without type 2 diabetes.

METHODS AND PROCEDURES

Twenty-one consecutive morbid obese subjects, 9 with type 2 diabetes (T2DM) and 12 with normal fasting glucose (NFG) were evaluated, just before and 1 month after BPD, by measuring body weight (BW), glucose, adipocitokines, homeostasis model assessment of insulin resistance (HOMA-IR), acute insulin response (AIR) to e.v. glucose and the insulinogenic index adjusted for insulin resistance ([DeltaI5/DeltaG5]/HOMA-IR).

RESULTS

Preoperatively, those with T2DM differed from those with NFG in showing higher levels of fasting glucose, reduced AIR (57.9 +/- 29.5 vs. 644.9 +/- 143.1 pmol/l, P < 0.01) and reduced adjusted insulinogenic index (1.0 +/- 0.5 vs. 17.6 +/- 3.9 1/mmol(2), P < 0.001). One month following BPD, in both groups BW was reduced (by approximately 11%), but all subjects were still severely obese; HOMA-IR and leptin decreased significanlty, while high-molecular weight (HMW) adiponectin and adjusted insulinogenic index increased. In the T2DM group, fasting glucose returned to non-diabetic values. AIR did not change in the NFG group, while in the T2DM group it showed a significant increase (from 58.0 +/- 29.5 to 273.8 +/- 47.2 pmol/l, P < 0.01). In the T2DM group, the AIR percentage variation from baseline was significantly related to changes in fasting glucose (r = 0.70, P = 0.02), suggesting an important relationship exists between impaired AIR and hyperglycaemia.

DISCUSSION

BPD is able to restore AIR in T2DM even just 1 month after surgery. AIR restoration is associated with normalization of fasting glucose concentrations.

Plasma visfatin concentrations in severely obese subjects are increased after intestinal bypass

OBJECTIVE

Visfatin has shown to be increased in obesity and in type 2 diabetes. The aim of this study was to determine the change in plasma visfatin in severely obese (SO) persons after weight loss following bariatric surgery in relation to glucose concentration.

RESEARCH METHODS AND PROCEDURES

Visfatin and leptin were studied in 53 SO persons (BMI, 54.4 +/- 6.8 kg/m(2)) before and 7 months after bariatric surgery and in 28 healthy persons (BMI, 26.8 +/- 3.8 kg/m(2)). All of the patients underwent bariatric surgery with biliopancreatic diversion or gastric bypass.

RESULTS

The pre-surgery levels of visfatin in the SO group were greater than in the control group (55.9 +/- 39.9 vs. 42.9 +/- 16.6 ng/mL, p = 0.024). This increase was significant in the SO group with impaired fasting glucose (63.4 +/- 36.6 ng/mL) and diabetes (60.0 +/- 46.0 ng/mL). SO patients with normal fasting glucose had similar levels of visfatin to the controls. Seven months after surgery, visfatin levels were significantly increased (84.8 +/- 32.8 ng/mL, p < 0.001). This increase was independent of the pre-surgical glucose levels. The type of bariatric surgery had no influence on visfatin levels. Post-surgical visfatin was significantly correlated with the post-surgery plasma concentrations of leptin (r = 0.39, p = 0.014).

DISCUSSION

Plasma levels of visfatin in the SO group were increased but only when accompanied by high glucose levels, even in the range of impaired fasting glucose. Bariatric surgery causes an increase in visfatin, which is correlated mainly with the changes produced in the leptin concentration.